Week-3 & 4 Week-3 & 4 The System Unit Mother Board CMOS, BIOS CMOS, BIOS Processor Machine Cycle System Clock Multi-Core Processor Basic Unit of Measurement Data Representation Memory RAM
Week-3 & 4Week-3 & 4The System Unit
Mother Board CMOS, BIOSCMOS, BIOS
Processor Machine Cycle System Clock Multi-Core Processor Basic Unit of Measurement Data Representation Memory
RAM
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System UnitSystem Unit The System Unit is a case which
is just like a box made up of a metalor plastic. This casing actually contain the electronic components of a computerused to process data.
The casing is some time called Chassis The most important component of this
System box is Mother Board. All the components are then installed on this Mother Board.
system unit
system unit
system unit
system unit
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The System UnitThe System Unit What are common components inside the system unit? Processor Memory Adapter cards
Sound card Modem card
Ports Drive bays Power supply
power supply
ports
drive bays
processor
memory
sound card
video cardmodem cardnetwork card
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Mother BoardMother Board It is the main circuit board of
the system unit. It is the centralized platform
where all the hardware componentsof a computer are connected.
Many electronic components are attached to the mother board, others are built-in on it.
The processor chips, memory chips & the other
components on the motherboard consist one or more chip’s.
Most chip’s are not bigger than one-half inch square.
processor chipadapter cards
memory chips
memory slots
motherboard
Expansionslots for adapter cards
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CMOS, BIOSCMOS, BIOS Each and every Motherboard has a small battery cell
“CMOS memory”. It gives to Motherboard a small amount of power to
remember the settings such as hardware configurations, date and time etc
BIOS is kind of software which holds the most important data for machine.
It informs the PC about the compatibility of Motherboard with different hardware components such as CPU etc…
It is the most important component which resides in the ROM CHIP (Read Only Memory) of the Motherboard.
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Mother Board (Cont’d)Mother Board (Cont’d) Small piece of semi-conducting material on which integrated
circuits are etched Two types of packaging for processor
and memory chip’s on desktop computersmotherboard
PGA It holds a larger number of pins,
these pins are mounted on the surface of the package.
DIP It consist two parallel rows of
downward pointing pins that attached to the circuit board.
pin grid array (PGA) package holds processor chips
dual inline packages (DIP) holds memory chips
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ProcessorProcessor The Processor is also called Central Processing Unit (CPU). All the CPUs looks very similar, but they are different in the
way, they have different numbers of pins and different layouts.
The processor significantly impact over all computing power & manages most of computer operations.
On larger computers, such as Mini or Mainframe computers, the various functions performed by the processor extend over many separate chips and often on multiple circuit boards.
On a personal computer, all function of the processor usually are on a single chip.
Some computer manufacturer use the term Microprocessor which refers to a personal computer chip.
Most PC’s today use processors manufactured by IntEL, AMD etc..
“Central Processing Unit (CPU) is an electronic device that interprets and carries out the instructions that operates the
computer.
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Processor (Cont’d)Processor (Cont’d)
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Processor (Processor (Cont’dCont’d)) The combination of Arithmetic Logic Unit and Control Unit is
called as Central Processing Unit (CPU). OR The two main parts of CPU are ALU & CU.
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Processor (Processor (Cont’dCont’d)) ARITHMETIC LOGIC UNIT (ALU)
This component of the computer is responsible for the actual processing.
This component is capable to perform all types of arithmetic operations such as addition, subtraction, multiplication and division etc.
Also it is capable to perform logical operations such as AND, OR etc. it is capable of comparison as well.
The ALU is connected to a set of registers—small & faster memory areas in the CPU, which hold data and program instructions while they are being processed.
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Processor (Processor (Cont’dCont’d)) Registers are the part of the processor, not a part of
memory or storage devices. It contain different type of registers, each with a specific
storage functions. E.g. General purpose registers used for arithmetic operations & data movement. AX, BX, CX, DX
Register function includes Storing the location from where an instruction is
fetched, Storing the location while the CU encode/decode it, Storing data while the ALU compute it and Storing the results after a calculation.
Today, most PCs have 32-bit registers, mean the CPU can process four bytes of data at one time.
Register sizes are rapidly growing to 64 bits.
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Processor (Processor (Cont’dCont’d)) ALU Operations List
Arithmetic Operations
LogicalOperations
+ Add , equal to, not equal to
Subtract >, > greater than, not greater than
x Multiply <, < less than, not less than
Divide , greater than or equal to, not greater than or equal to
^ Raise by a power , less than or equal to, not less than or equal to
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Processor (Cont’d)Processor (Cont’d) CONTROL UNIT (CU)
This unit is responsible for the overall supervision of the computer system.
It does not perform the actual processing but by reading and interpreting the instructions contained in a program, Control Unit (CU) directs other unit of the system to perform a specific task.
Control unit (CU) behaves like a traffic police instructor. It manages the functions performed by different parts of computer.
It controls and coordinates the entire computer system, just the brain directs the human body.
It is responsible to accept data from input device and send it to the memory, from memory to ALU, finally CU sent back the results and store in the memory, until the results are released to an output device.
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Machine CycleMachine Cycle The CPU follows a set of steps-called a machine cycle-for each
instruction it carries out. By using a technique called pipelining, many CPUs can process
more than one instruction at a time. Four operations of the CPU comprise a machine cycle
Step 2. Decode Translate instruction into commands
Processor
Control Unit
Memory
ALU
Step 1. Fetch Obtain program instruction or data item from memory
Step 4. Store Write result to memory
Step 3. Execute Carry out command
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System ClockSystem Clock
Each tick Each tick is a is a
clock cycleclock cycle
Pace of system Pace of system clock is clock is clock speedclock speed
Most clock speeds are Most clock speeds are in the gigahertz (GHz) in the gigahertz (GHz)
range (1 GHz = one range (1 GHz = one billion ticks of system billion ticks of system
clock per second)clock per second)
Processor speed can Processor speed can also be measured in also be measured in
mmillions of illions of iinstructions nstructions pper er ssecond econd (MIPS) or in FLOPs(MIPS) or in FLOPs
Controls timing of all computer operations Generates regular electronic pulses, or ticks, that
set operating pace of components of system unit
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Heat SinkHeat Sink Heat sink—
component with fans that cools processor
heat sink fan
heat sink
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Parallel ProcessingParallel Processing
Control ProcessorControl Processor
Processor 1Processor 1
MemoryMemory
Processor 2Processor 2
MemoryMemory
Processor 3Processor 3
MemoryMemory
Processor 4Processor 4
MemoryMemory
Results combined
Using multiple processors simultaneously to execute a program faster
Requires special software to divide problem and bring results together
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Multi-Core ProcessorMulti-Core Processor A Multi-Core Processor is a processing system composed of two
or more independent cores. The cores are typically integrated onto a single integrated circuit die(known as a chip multiprocessor or CMP).
Core Basic processing area of a computer processor Die A die in the context of integrated circuits is a small block of
semiconducting material, on which a given functional circuit is fabricated.
A medium-scale integrated circuit die
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Multi-Core Processor Multi-Core Processor (Cont’d)(Cont’d)
A Dual-Core and Core 2 Duo Processor contains two cores, and a Quad-Core Processor contains four cores.
A Multi-core processor implements multiprocessing in a single physical package.
Cores in a multi-core device coupled together tightly. Cores may or may not share caches. Dual Core and Core 2 Duo’s are both dual core processor. Core2 duo only takes advantage because The Core 2 Duo has the same L2 cache but it has more cache size
than a Dual core. However, There are architectural changes to the silicon that give the Core 2
Duo more sophisticated processing. The single- and dual-core models are single-die, whereas the
quad-core models comprise two dies, each containing two cores, packaged in a multi-chip module.
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Basic Units Of MeasurementBasic Units Of Measurement BIT
BInary digiT Smallest unit of measurement Two possible values 0 & 1
ON OFF or
BYTE
8 bits
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Data RepresentationData Representation
Recognize only two discrete states: on or off
Use a binary system to recognize two states
Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)
Most computers are digital
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Data Representation Data Representation (Cont’d)(Cont’d)
Eight bits grouped together as a unit Provides enough different combinations of 0s
and 1s to represent 256 individual characters Numbers Uppercase
and lowercase letters
Punctuation marks
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Data Representation Data Representation (Cont’d)(Cont’d)
ASCII—American Standard Code for Information Interchange
EBCDIC—Extended Binary Coded Decimal Interchange Code
Unicode—coding scheme capable of representing allworld’s languages
ASCII Symbol EBCDIC
00110000 0 11110000
00110001 1 11110001
00110010 2 11110010
00110011 3 11110011
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Data Representation Data Representation (Cont’d)(Cont’d)
How is a letter converted to binary form and back?
Step 1.The user presses the capital letter D (shift+D key) on the keyboard.
Step 2.An electronic signal for the capital letter D is sent to the system unit.
Step 3.The signal for the capital letter D is converted to its ASCII binary code (01000100) and is stored in memory for processing.
Step 4.After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device.
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Basic Units Of Measurement Basic Units Of Measurement ((Processor And Memory Speed))
Millisecond (ms) – a thousandth of a second (1/1,000 = 10-3) Microsecond (µs) - a millionth of a second (1/1,000,000 = 10-6) Nanosecond (ns) – a billionth of a second (1/1,000,000,000 = 10-
9)
Large Units Of Measurement (Memory, Storage) Note: powers of two are used because computer memory and
storage are based on the basic unit (bit). Kilobyte (KB) – a thousand bytes (1,024 = 210) Megabyte (MB) -1,024 KB - a million (1,048,576 = 220) Gigabyte (GB) –1,024 MB - a billion (1,073,741,824 = 230) Terabyte (TB) – a trillion (1,099,511,627,776 = 240)
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Memory The electronic component which provides storage capability to a
computer is called Memory. Memory contains one or more sets of
chips that store data/program instructions need processing, either temporarily or permanently.
All the computers which are used today needs memory or storage capability.
The CPU accesses each location in memory by using a unique number, called the memory address.
Each byte stored in unique location called an address, similar to addresses on a passenger train
Seat #2B4 Seat #2B3
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Memory Memory (Cont’d)(Cont’d)
The are two types of Memory Random Access Memory Read Only Memory
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Random Access MemoryRandom Access Memory RAM is also called volatile memory and Keeps the
information for a shorter period of time because RAM Lost information if powered off or the computer is shutdown.
RAM store data or instructions, the computer then uses these instructions to perform any processing work.
The contents of RAM change rapidly and often. Typical ranges from Mega Bytes to Giga Bytes Random Access means direct access to any part of memory
The more RAM a The more RAM a computer has, the computer has, the faster it respondsfaster it responds
Also called Also called main memorymain memory
or or primary primary storagestorage
Most RAM is Most RAM is volatilevolatile, it is lost , it is lost when computer’s when computer’s
power is power is turned offturned off
Memory chips that can be Memory chips that can be read from and written read from and written
to by processorto by processor
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How do program instructions transfer in and out of How do program instructions transfer in and out of RAM?RAM?
Step 1. When you start the computer, certain operating system files load into RAM from the hard disk. The operating system displays the user interface on the screen.
Operating system Operating system instructionsinstructions
Operating system Operating system interfaceinterface
RAM
RAM
Web browser Web browser program instructions program instructions
are removed from are removed from RAMRAM
Web browser Web browser window no longer window no longer
is displayed on is displayed on desktopdesktop
Step 2. When you start a word processing program, the program’s instructions load into RAM from the hard disk. The word processing program, along with the Web Browser and certain operating system instructions are in RAM. The word processing program window is displayed on the screen.
Step 3. When you quit a program, such as the Web browser, its program instructions are removed from RAM. The Web browser no longer is displayed on the screen.
Word processing Word processing program program instructionsinstructions
Word processing Word processing program windowprogram window
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Where does Memory Reside?Where does Memory Reside?
Resides on small Resides on small circuit board called circuit board called memory modulememory module
Memory slotsMemory slots on on motherboard hold motherboard hold memory modulesmemory modules
memory chip memory slot
dual inline memory module